Since 1988, over 19,000 rap songs have made reference to marijuana and cocaine. Far fewer have mentioned prescription drugs, Codeine and MDMA, though Sizzurp, that foul concoction of promethazine and codeine cough syrup, soda, and Jolly Ranchers, seems to be having a resurgence. Meanwhile, rappers seem less interested in calling out specific alcohol brands today than they did in the mid 1990s.

These are some of the observations from Drug Slang in Hip Hop, a series of graphs that catalog drug references in rap lyrics between the late ’80s through 2013. The charts break each drug into its various nicknames–i.e. cocaine, blow, piff, and eight ball–and show the “prevalence” of each name in a given year. (Prevalence is the number of songs with a specific drug reference divided by the total number of songs released that year.)

The graphs, which are based on a study of RapGenius lyrics, were commissioned by Project Know, an online resource for families and friends whose loved ones are struggling with drug and alcohol addiction. Mostly, it’s fascinating to see the spectrum of names for a single substance–and to speculate about the ebb and flow of their popularity. It’s striking, for example, to see the explosion in the number and overall volume of prescription drugs mentioned around 2006, and the rise of Adderall. “Along with the steep rise in various pain killers, including Percs, Lortab, and hydrocodone since the mid-2000s, Adderall’s popularity has surged,” the researchers have said.

It’s also interesting to see the rise and fall in popularity of certain alcohol brands, including a Patron spike starting in 2003, and the inexplicable durability of Hennessy.